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SSL_SESSION_get0_hostname, SSL_SESSION_set1_hostname, SSL_SESSION_get0_alpn_selected, SSL_SESSION_set1_alpn_selected - get and set SNI and ALPN data associated with a session


 #include <openssl/ssl.h>

 const char *SSL_SESSION_get0_hostname(const SSL_SESSION *s);
 int SSL_SESSION_set1_hostname(SSL_SESSION *s, const char *hostname);

 void SSL_SESSION_get0_alpn_selected(const SSL_SESSION *s,
                                     const unsigned char **alpn,
                                     size_t *len);
 int SSL_SESSION_set1_alpn_selected(SSL_SESSION *s, const unsigned char *alpn,
                                    size_t len);


SSL_SESSION_get0_hostname() retrieves the SNI value that was sent by the client when the session was created, or NULL if no value was sent.

The value returned is a pointer to memory maintained within s and should not be free'd.

SSL_SESSION_set1_hostname() sets the SNI value for the hostname to a copy of the string provided in hostname.

SSL_SESSION_get0_alpn_selected() retrieves the selected ALPN protocol for this session and its associated length in bytes. The returned value of *alpn is a pointer to memory maintained within s and should not be free'd.

SSL_SESSION_set1_alpn_selected() sets the ALPN protocol for this session to the value in alpn which should be of length len bytes. A copy of the input value is made, and the caller retains ownership of the memory pointed to by alpn.


SSL_SESSION_get0_hostname() returns either a string or NULL based on if there is the SNI value sent by client.

SSL_SESSION_set1_hostname() returns 1 on success or 0 on error.

SSL_SESSION_set1_alpn_selected() returns 1 on success or 0 on error.


ssl(7), d2i_SSL_SESSION(3), SSL_SESSION_get_time(3), SSL_SESSION_free(3)


The SSL_SESSION_set1_hostname(), SSL_SESSION_get0_alpn_selected() and SSL_SESSION_set1_alpn_selected() functions were added in OpenSSL 1.1.1.


Copyright 2016-2019 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <>.

2020-04-20 1.1.1d